The present invention relates to a heat exchanger which has a connector for connecting with a receiver tank and brazed to a header pipe, and the receiver tank connected with the connector by male screw parts.
Generally, a heat exchanger used for a vapor compression type refrigerating cycle or the like of an air-conditioning device for vehicles is known comprised of heat-exchanging tubes for a cooling medium connected with header pipes for distributing and collecting the cooling medium, and a receiver tank for temporarily accumulating the aggregated cooling medium connected with the header pipe (for example, a condenser described in Japanese Patent Application Laid-Open Publication No. 9-217967).
As such a type of heat exchanger, in addition to one configured to supply the cooling medium accumulated in the receiver tank directly to an evaporator, there is especially known a so-called sub-cool condenser which is configured to send the cooling medium accumulated in the receiver tank back to the header pipe, to further cool it in the tubes and to supply to the evaporator. This sub-cool condenser can improve a cooling efficiency of the cooling medium.
Besides, the heat exchanger has the header pipe and the receiver tank connected with a connector 8 interposed therebetween as shown in FIG. 4(A) and FIG. 4(B).
The connector 8 shown in the drawings is used for the aforesaid sub-cool condenser, brazed to the header pipe and also connected to the receiver tank by a male screw part such as a bolt.
Specifically, an outflow path 81 for outflowing the cooling medium to the receiver tank and an inflow path 82 for inflowing the cooling medium from the receiver tank are disposed between a brazing face 8a against the header pipe and a mating face 8b against the receiver tank, and a hole 83 into which the male screw part is screwed is formed on the mating face 8b. 
Conventionally, the connectors of the aforesaid heat exchanger need to form the hole into which the male screw part is inserted or screwed and therefore must be formed large to some extent. As a result, there was a disadvantage that the heat exchanger becomes large and heavy.
Especially, where the heat exchanger is mounted on a vehicle, it was very disadvantageous to use a large and heavy connector in terms of arrangement with other devices.
And, where the connector is large, the heat capacity required for brazing the header pipe and the connector increases, resulting in a disadvantage that their brazing becomes difficult.
In addition, the connector used for the sub-cool condenser has the outflow path for outflowing the cooling medium to the receiver tank and the inflow path for inflowing the cooling medium from the receiver tank positioned on the mating face with the receiver tank as described above. Therefore there was also a disadvantage that it was difficult to balance a supporting strength between the receiver tank and the connector by the male screw part.
On the brazing face between the header pipe and the connector, bypass leakage might be caused in the outflow path and the inflow path due to a defective brazing. Such bypass leakage becomes a cause of considerable lowering of the function of the heat exchanger but its detection is quite difficult because it does not involve external leakage.
In view of the aforesaid drawbacks, it is an object of the invention to provide a heat exchanger which can efficiently connect the header pipe and the receiver tank.
The invention recited in claim 1 is a heat exchanger comprising tubes for heat-exchanging a cooling medium, header pipes connected to the tubes for distributing and collecting the cooling medium and a receiver tank connected to the header pipe for temporarily storing the cooling medium, the header pipe being provided with a connector by brazing for connecting with the receiver tank, and the receiver tank and the connector being connected by male screw parts, wherein
the connector has a brazing face along a longitudinal direction of the header pipe and which has a curvature to externally fit the header pipe, and a mating face to be connected to the receiver tank;
the connector has an outflow path for outflowing the cooling medium from the header pipe to the receiver tank, an inflow path for inflowing the cooling medium from the receiver tank to the header pipe, and a plurality of holes into which a plurality of the male screw parts are inserted or screwed;
the connector is so formed that its brazing face against the header pipe is narrower than a mating face of the receiver tank and a plurality of holes into which the male screw parts are inserted or screwed formed on the mating face larger than the brazing face; and
the connector is formed with a groove between the inflow path and the outflow path on the brazing face against the header pipe so to divide the brazing face.
Thus, according to the heat exchanger of the invention, the connector is formed to have the brazing face against the header pipe narrower than the mating face against the receiver tank, so that the connector is formed to have a reduced size and weight, and the brazing property between the header pipe and the connector is improved.
Specifically, the connector connected to the receiver tank by the male screw parts needs holes into which the male screw parts are inserted or screwed and has to be formed to have a predetermined large size, causing a disadvantage of making the heat exchanger large in size and heavy. But, according to the connector of the invention, the brazing face against the header pipe is formed to be narrower than the mating face against the receiver tank, allowing to make the connector smaller and lighter in weight and reducing the above disadvantages.
Particularly, where the heat exchanger is mounted on a vehicle or the like, a disadvantage involved in the layout with other devices can be reduced because a relatively small and lightweight connector is used.
Where the connector is large, the heat capacity required for brazing the header pipe and the connector increases. But, according to the present invention, the increase in the heat capacity is avoided and the brazing property is improved because the brazing face against the header pipe is narrower than the mating face against the receiver tank.
And, according to the heat exchanger of the invention, the connector has the outflow path for outflowing the cooling medium to the receiver tank, the inflow path for inflowing the cooling medium from the receiver tank, and the groove formed between the inflow path and the outflow path on the brazing face against the header pipe so to divide the brazing face. Therefore, on the brazing face between the header pipe and the connector, bypass leakage which might be caused in the outflow path and the inflow path due to a defect in brazing can be detected readily because the leakage becomes external leakage through the groove.
The bypass leakage in the outflow path and the inflow path considerably lowers the function of the heat exchanger but its detection was quite difficult. According to the present invention, even such a bypass leakage can be detected as an external leakage by virtue of the groove.